Please help determing this resistor value.

[Will_V]

Hi,

I got this resistor out of a non-functioning Motormaster battery charger circuit board. The heat may have altered the color code. Please help me determining this resistor value so can save this charger from going to the landfill.

Cheers,

Will

 

[Harald Kapp]

No chance without a schematic - or someone who owns the same make and is willing to look up the color code in his charger.

What exat type is the charger?

 

[Will_V]

I bought it from Canadian Tire. It is a Motormaster 10/2A battery charger.

 

[Harald Kapp]

I'm sorry I can't help, but hopefully some owner of a working charger is willing to look up the color code for you.

 

[(*steve*)]

There seem to be some markings on the other side. What do they say?

Have you measured the resistance? What is it?

 

[ICGengineerTech]

You should take a picture of the other side, measure the resistance, and you could always guess using a pot.

 

[Jamie7]

Will,

There is a clue there. You see the zener right below? This resistor is likely the current limiting resistor feeding the supply voltage to this zener. The resistor keeps the zener from burning up. I would guess that this resistor is about 100-120 ohms.
Try a 120 ohm resistor there at the wattage of this resistor. Probably about 1/2 -1 Watt. This part of the circuit is part of the control circuit and there is not a high current flowing here. So feel safe to try this. I think you will find it will work. Also this resistor will get warm. Use a larger wattage if this one is burning up frequently. Also check to make sure the zener has not shorted. This will cause the resistor to burn.

Addt'l info: Also, if there is a bad IC or another part that has failed this will also cause a higher than usual current to flow through the resistor and make it overheat. Try looking at the traces on the other side and see if the left side of the resistor goes to the zener. Also the right side of the resistor also looks like it goes to the larger electrolytic cap. If this is the case try to test the zener to see if it is okay before you try another resistor.

Good Luck, Jamie

 

[(*steve*)]

I would be wondering if the resistor is actually damaged. It looks like the board is a little heated, but I see no damage to the resistor.

 

[Jamie7]

Yes, this may be true. It would be good to measure this resistor. It looks like the leads are long and the resistor is up off of the board some also. Some resistors can look like this and be okay still.
I have seen this before. He will have to make measurements to complete the analysis and conclude what is actually the condition of the resistor.
I pointed out the circuit and what is happening there so if he has some smarts, he may be able to determine what is wrong, if any in this section.
If there is no other info then knowing something about the circuit will most definitaly be helpful, .....indeed!
He could send me the board and I could then tell him the answer to his dilemma.
But... that is probably not a cost effective option....